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1. Part 1
For each question:
a) State the null and alternative hypothesis for a test to determine the validity of the claim
b) Identify left, right, or two-tailed test type
1. The average miniature horse is less than 34 inches at the shoulder. Tiny Equines claims
that their miniature horses are an average of 3 inches less than the breed average.
2. Speedy Solutions is a delivery company that claims all deliveries average less than 72
hours.
3. Terrific Textiles claims that 45% to 55% of t-shirts sold in CO are red.
4. Gas Hater Car Sales claims that 70% or more of the cars on the lot average more than
40 mpg.
5. The 2011 average service time for Fast Fatz Burgers was 56 seconds. The store
manager claims that the 2012 average is more than 5 seconds faster.
6. Colorful Cavity Causers sells multi-colored candies by the bag. Each bag is claimed to
average between 5.5 and 6.5 oz.
7. Aaron works for an electronics company, quality-testing batteries. The company claims a
minimum of 5 hrs battery life.
8. The lessons in this Probability and Statistics text average 13 practice problems each.
9. The outside temperature in Maui averages between 72 and 83 degrees year-round.
10. 72% of elementary school teachers are female.
Part 2
1. The school nurse thinks the average height of 7th graders has increased. The average
height of a 7th grader five years ago was 145 cm with a standard deviation of 20 cm.
She takes a random sample of 200 students and finds that the average height of her
sample is 147 cm. Are 7th graders now taller than they were before? Conduct a single-
tailed hypothesis test using a .05 significance level to evaluate the null and alternative
hypotheses.
2. A farmer is trying out a planting technique that he hopes will increase the yield on his
pea plants. The average number of pods on one of his pea plants is 145 pods with a
standard deviation of 100 pods. This year, after tryinghis new planting technique, he
takes a random sample of his plants and finds the average number of pods to be 147.
He wonders whether or not this is a statistically significant increase. What are his
hypotheses and the test statistic? N = 200.
3. The high school athletic director is asked if football players are doing as well
academically as the other student athletes. We know from a previous study that the
average GPA for the student athletes is 3.10. After an initiative to help improve the GPA
of student athletes, the athletic director randomly samples 20 football players and finds
tha the average GPA of the sample is 3.18 with a sample standard deviation of 0.54. Is
there a significant improvement?Use a 0.05 significance level.
4. Duracell manufactures batteries that the CEO claims will last an average of 300 hours
under normal use. A researcher randomly selected 20 batteries from the production line
and tested these batteries. The tested batteries had a mean life span of 270 hours with a

2. standard deviation of 50 hours. Do we have enough evidence to suggest that the claimof
an average lifetime of 300 hours is false?